The Buzz About Bees

A couple of decades ago, your associations with bees might have been enumerated in a simple list: painful stings, honey makers, villains that made you cry in the 1991 movie My Girl.

These days, you’re more likely to associate bees with the stuff of apocalypse: colony collapse disorder, deadly pesticides used by big agriculture, a lethal bug called the varroa mite—all serious threats to food production. A quick Google search for recent articles about bees delivers the following titles: “Why Are Bees Vanishing?” “The Blight of the Honeybee” “What Is Killing America’s Bees and What Does It Mean for Us?” Even President Obama, nicknamed by some as the Pollinator-in-Chief, is concerned about the bees and said to question in Oval Office meetings whether we’re doing enough to save them.

The Bee Informed Partnership recently reported that beekeepers lost almost half their colonies between April 2015 and March 2016. Though they’re not in danger of extinction (at least not yet), bees are dying at an alarming rate, and most scientists say human activity is killing them. The irony, of course, is that without them, we can’t eat. Through pollination, bees are responsible for one out of every three bites we put in our mouths. They’ve become an agricultural commodity valued at $15 billion annually in the United States alone, yet the pesticides that beekeepers use are one of the main causes of their decline—along with the varroa mite and some lesser factors, such as other diseases, loss of habitat to humans, and an increasingly monotonous diet.

Connections between the predicament of these insects and the future of our environment are the crux of how Michelle Hersh structured her spring seminar course, “Global Change Biology,” in which students explored how global ecosystems are being altered by human activities. “We focus on the biological impacts of climate change and other major environmental issues, in light of the physical changes happening,” Hersh explains. For example, her class looked at how changing temperatures affect the relative timing of seasonal changes, like when migrating birds appear, flowers bloom, and marmots awake from hibernation. Reading dozens of scientific journal articles and other primary sources, her students explored how the extensive use of fertilizers upstream in a large river can affect biological communities downstream, how overfishing might be altering marine biodiversity, and other important questions. They also designed potential campus sustainability initiatives, including installing low-flow showerheads and faucets (which use aerators to mix air with water, allowing the same wetness with less water) and collecting rainwater in 10,000-gallon tanks. In this session of the course—which was part of a two-week unit on sustainable agriculture—Hersh’s students wondered: What are the specific threats to bee health, and how might they be interconnected?

Michelle Hersh: We have a really interesting set of papers to discuss today that follow up on our discussion about agriculture and biotechnology, and the importance of pollination and various threats to bees. … Let’s think about … the multiple stressors that are affecting bee populations. … What are some of the factors that bees need to survive successfully in the wild or in colonies? …

Joe Sterling ’16:... Wildflowers.

Lily Frenette ’18: Undisturbed nest sites.

Jesenia Fuentes ’16: … A diversity of food sources.

Hersh: [Writing on chalkboard] Right, the right balance of available nutrients … and consistent flowering [of plants].

Hersh: … And protection from predators. Water’s pretty nice, too. … What are the threats bee pollination is facing currently?

Frenette: Habitat loss. … Urbanization, which increases traffic through the [bee’s habitat], which results in less plants. … Less food sources in urban areas, and less diverse food sources.

Hersh: … Why would we see less diverse food sources in different kinds of bee habitats?

Leyana Dessauer ’17: Urbanized areas can have less biodiversity. …

Frenette: Natural areas, like forests and prairies, [are] being changed into farmland, which means that an area that used to have a lot of flowers and diverse plants has become a monoculture, with only one type of food.

Hersh: Right. … There’s a great sentence in [the Goulson] paper… “If a human were to consume nothing but sardines one month, chocolate the next, turnips the month after, and so on, one could reasonably expect that person to fall ill. This may seem like a frivolous example, but it is a reasonable parallel to the experience of some honeybee colonies.” … What else?

Sterling: Pesticides.

Zoe Berg ’18: Parasites.

Dessauer: … Stress from being shipped long distances.

Hersh: What are some other issues with trade?

Fuentes: Shipping species that are not indigenous to the area, which can possibly wipe out the ones that are indigenous.

Hersh: Translocation of species, but with shipping, what else gets transported to the area?

Class: More parasites.

Anna Rossi ’18: … Competition [is another threat].

Frenette: … Like Jessie was saying, the shipped bees compete with other pollinators.

Hersh: … What are some other ways that stressors [or threats] are interacting? [For example], you could think about the varroa mite and viruses as these two different stressors—one is an ectoparasite and one is a virus—and the ectoparasite facilitates the spread of the virus. …

Sterling: There are some pathogens that when the bees were healthy and well fed, there was a relatively low mortality rate, then when they were having a monotonous diet and not enough food, [the pathogen] became more of a problem.

“The combination of all of these separate stressors creates one big problem of declining bee populations, which then becomes a threat to our food sources.”

Frenette: … A certain fungicide [on its own] is very low in toxicity, but when it interacted with a bee [exposed to] neonicotinoids (an insecticide) … the toxicity increased by as much as 1,000 times.

Hersh: Any other examples of interacting stressors? There’s another really colorful sentence in [the Goulson article]—

Frenette: —Oh, is it the one about the man smoking? (Reads from article) “If a middle-aged man who is overweight, does little exercise, and smokes and drinks heavily were to die of a heart attack, we would not be surprised, and we might not spend too long arguing over which single risk factor was most important in bringing about his untimely demise.”

Hersh: … The combination of all of these separate stressors creates one big problem of declining bee populations, which then becomes a threat to our food sources. But when we think about these individual stressors one at a time, we realize there are also many different actions that can be taken at different scales—by individuals, by governments, by farms—to try to improve bee health.